The invention relates to sliders for near-field optical data storage. More particularly, the invention relates to optical components mounted on a slider suitable for a near-field optical data storage and retrieval.
Optical data storage disc systems are useful for storing large quantities of data. The data is accessed by focusing a light beam, generally a laser beam, onto a data surface of a disc and detecting light reflected from or transmitted through the data surface. In general, in optical data storage systems, data is in the form of physical or magnetic marks carried on the surface of the disc. The physical or magnetic marks are detected using the reflected laser light.
There are a number of different optical disc technologies that are known in the industry. For example, compact discs currently are used to store digital data computer programs or digitized music. Typically, compact discs are permanently recorded during manufacture. Another type of optical system involves a write-once-read-many (WORM) system in which a user can write information permanently onto a disc. In addition, phase change and magneto-optic (M-O) systems provide erasable optical disc systems, which are clearly desirable for certain applications. Phase change systems detect data by sensing a change in reflectivity. M-O systems read data by measuring the rotation of the incident light polarization due to the storage medium.
High density optical storage can make use of near-field optical techniques. Near-field optical recording makes use of optical coupling between optical components on the slider with the surface of the optical disc. This optical coupling involves both evanescent fields near the surface of the slider and fields that propagate in air to focus objects very close to the slider. Generally, M-O and phase change systems use near-field optical techniques.
Near-field optical recording can be accomplished by focusing the beam through a pinhole that is smaller than the diffraction limited spot size. Alternatively, the beam can be focused through a Solid-Immersion-Lens (SIL). As described in U.S. Pat. No. 5,125,750 to Corle et al., the SIL is a spherical optical component, having a surface coinciding with a portion of a sphere, that is located with the center of the sphere approximately at the focal point of an objective lens.